A virtual reality game is helping people with dementia and leading to a drastic reduction in medication needed for some patients.

The "Virtual Forest" allows users to sit in front of a screen and use simple hand movements to cause changes in the landscape shown in the game.

It does not require headsets or hand controls and the scenery includes elements such as butterflies fluttering through flowers, a rowboat floating around a pond or a family of ducks splashing about in the water.

Dr Tanya Petrovich, a tech developer with Alzheimer's Australia, said early findings showed the virtual reality experience made significant changes to the quality of life of many users.

"It had to be intuitive as well, because for a person living with dementia, you can't give them a whole set of, 'these are the rules of the game'," she said.

"It had to be something that was really intuitive and easy to understand so the person can, without any instruction, understand how to play the game.

"The park-like setting that we've got, with lots of trees and flowers and people engaging through actions of their hands — we know that those are the elements that would help to create this very calm interaction for people."

Dementia is the second leading cause of death in Australia and more than 350,000 people currently live with the condition.

There is no cure and it is estimated the number of patients will increase to about 900,000 in Australia by 2050.